The invention relates to a method and a control system for operating an internal combustion engine that takes in a mixture and has an intake tract, electromechanically activated charge cycle valves, an ignition system, and an injection system.
There exist prior art internal combustion engines whose charge cycle valves are activated electromechanically. In contrast to camshaft-activated valves, these valves are actuated so as to open and close as a function of the rotational position of the crankshaft; there is no fixed mechanical coupling to the crankshaft. Electromechanical final positioning elements of the charge cycle valves could have a different construction.
In European Patent Application 0 493 634 A1, corresponding to U.S. Pat. No. 5,072,700 to Kawamura, for example, charge cycle valves are described that are closed by a valve spring and opened by an electromagnet. The charge cycle valves disclosed in German Utility Model 297 19 502 U1, corresponding to U.S. Pat. No. 5,980,235 to Eppich et al. or European Patent Application 0 724 067 A1, corresponding to U.S. Pat. No. 5,752,478 to Sono et al. and U.S. Pat. No. 5,765,514 to Sono et al., have, in contrast, a position of rest that is located between a closed position and an open position and from which they can be deflected by electromagnets. Such configurations are referred to below as two-spring valves.
In order to open or close such a two-spring valve, the respective winding is energized, the necessary current being greater in the capture phase than in the holding phase in which the valve is held in an end position.
Whereas the control times in the operational control unit of the internal combustion engine are not predefined in conventional, camshaft-activated valve drive, it is necessary to calculate and predefine appropriate control times in the case of electromechanically activated valves.
Internal combustion engines with electromechanically activated valves, therefore, generally have, in addition to the normal operational control unit of the internal combustion engine, a control unit for the electromechanically activated valves, which control unit actuates the electromechanically activated valves based on the crankshaft position signal and the predefined values of the operational control unit.
In European Patent Application 0 493 634 A1, an electromagnetically activated auxiliary valve is provided in addition to the electromagnetically activated charge cycle valves. The auxiliary valve is located in parallel with the outlet valve and is opened before it to reduce the pressure against which the outlet valve has to open. All the valves have a closed position of rest. In the event of a failure, the auxiliary valve remains closed by virtue of its construction. The respective cylinder is, then, deactivated.
In the event of a failure of the electromechanical activation of a two-spring valve, which can take place, for example, as a result of (1) a failure of the final positioning element, (2) the output stage that actuates the final positioning element, or (3) a fault in the control unit and, under certain circumstances, only occurs briefly, the respective valve remains open, which is undesirable.
If such a failure occurs in an inlet valve, ignition into the intake manifold or into the intake tract may occur.
If such a failure occurs in an outlet valve, the ignition may occur in the exhaust tract and the emission control system may be damaged.
It is accordingly an object of the invention to provide a control system and method for operating an internal combustion engine that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that has electromechanically activated charge cycle valves with a half-open position of rest so that, even in the event of a failure of an electromechanically activated charge cycle valve, an undesired ignition of fuel/air mixture into the intake tract or exhaust tract can be avoided.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a control system for an internal combustion engine that receives a fuel/air mixture and has an intake tract, electromechanically activated charge cycle valves each having an open end position, a half-open position of rest, a closed end position, and two electromagnets selectively moving a charge cycle valve into the open end position and the closed end position and holding the charge cycle valve in a respective position, an ignition system, and an injection system, the control system including a control device for monitoring an operational capability of the charge cycle valves, the control device connected to the ignition system and the injection system and actuating the ignition system and the injection system, the control device programmed to prohibit an injection at the injection system and to prevent undesired ignition of the fuel/air mixture when a charge cycle valve exhibits a faulty function by either one of not closing and not closing completely, the control device having assemblies each programmed to detect the faulty it function of the charge cycle valves, OR elements each having, inputs, and an output connected to at least one of the injection and ignition systems for actuating at least one of the injection and ignition systems, and signal lines connecting each of the assemblies to an input of a respective one of the OR elements.
According to the invention, in the event of a failure of a charge cycle valve, as a result of which the charge cycle valve would remain open, the injection is suppressed and/or the ignition is shut down, for example, by intervention in the ignition coil. As a result, when a valve failure is detected, no combustible fuel/air mixture is generated or ignited, at least in the cylinder in question, as a result of which an undesired ignition into the outlet or exhaust tract is prevented.
The shutting down of the injection and the suppression of the ignition can be carried out for all cylinders, but is also possible on a cylinder-specific basis.
In accordance with another feature of the invention, the assemblies include travel controllers assigned to the charge cycle valves, and a valve control unit is connected to the travel controllers.
In accordance with a further feature of the invention, there is provided an operational control unit connected to each of the outputs of the OR elements and to at least one of the injection and ignition systems, each of the outputs of the OR elements indirectly intervening in at least one of the injection and ignition systems through the operational control unit.
In one advantageous refinement of the invention, a control unit for the electromechanically activated inlet valves signals a failure of a valve to the operational control unit of the internal combustion engine, which subsequently prohibits the injection and/or the ignition at least for the cylinder in question.
In accordance with an added feature of the invention, each of the outputs of the OR elements directly intervening in at least one of the injection and ignition systems.
In accordance with an additional feature of the invention, the injection system has a voltage supply, the ignition system has a voltage supply, a switch is connected to the voltage supply of the injection system and the voltage supply of the ignition system, and the control device is programmed to shut off, through the switch, the voltage supply of at least one of a part of the injection system, and a part of the ignition system.
In accordance with yet another feature of the invention, the internal combustion engine has cylinders each having one of the charge cycle valves, and when a charge cycle valve fails, the valve control unit is programmed to first prohibit at least one of the group consisting of injection at the injection system and ignition at the ignition system for all the cylinders and, at the same time, the valve control unit is programmed to output a message to the operational control unit to bypass an intervention of the valve control unit for at least one of the injection and ignition systems and to bring about a cylinder-specific shut-down of at least one of the injection and ignition systems, during which shut-down only a cylinder whose respective charge cycle valve fails is shut down.
With the objects of the invention in view, there is also provided a method of monitoring an operational capability of charge cycle valves of an internal combustion engine, including the steps of providing an internal combustion engine receiving a fuel/air mixture, monitoring an operational capability of the charge cycle valves with a control device, prohibiting an injection at the injection system with the control device to prevent undesired ignition of the fuel/air mixture when a charge cycle valve exhibits a faulty function by either one of not closing and of not closing completely, connecting assemblies of the control device to each input of a respective one of OR elements with a signal line, detecting the faulty function of each of the charge cycle valves with the assemblies, and actuating at least one of the injection and ignition systems with an output of the OR elements.
In accordance with yet a further mode of the invention, at least one of the injection and ignition systems is directly intervened or indirectly intervened via an operational control unit through an output of an OR element
In accordance with yet an added mode of the invention, the control device shuts off a voltage supply of at least part of one of the injection and ignition systems by a switch.
In accordance with a concomitant mode of the invention, the valve control unit first prohibits at least one of an injection at the injection system and an ignition at the ignition system for all cylinders when a charge cycle valve fails, and, at the same time, the control device outputs a message to the operational control unit to bypass the intervention of the valve control unit in at least one of the injection and ignition systems and to bring about a cylinder-specific shut-down of at least one of the injection and ignition systems, during which shut-down only a cylinder whose charge cycle valve fails is shut down.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a control system and method for operating an internal combustion engine, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.